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Genetics > Exam 1: Lecture 6 & 7 > Flashcards

Exam 1: Lecture 6 & 7 Flashcards

1
Q

define genetic linkage

A

tendency of alleles that are located close together on a chromosome to be inherited together during meiosis linked genes will segregate togehter and not obery mendels 2nd law

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2
Q

linkage disequilibrium

A

the non-random association of alleles at diff loci

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3
Q

what can restore random segregation

A

meiosis/recombination

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4
Q

what are complex inheritance of traits

A

some traits, like human stature, are produced by the interplay of many sets of genes; these are known as “polygenic” traits

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5
Q

what is a single gene disorder

A

single mutated gene causes a disorder

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6
Q

what is non-mendelian inheritance

A

any pattern of inheritance in which traits do not segregate with mendel’s laws

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7
Q

snail chirality

A

is based on determining polarity in early embryo; earliest and important events in embryo development

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8
Q

genes at the same locus

A

two versions of the same gene; each version of the same gene is defined as allele ex blood type

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9
Q

mendel’s traits all exhibited _

A

complete dominance

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10
Q

define complete dominance

A

phenotype of the heterozygote is the same as the phenotype of homozygous dominant

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11
Q

define incomplete dominance

A

phenotype of the heterozygote is intermediate (fails w/in the range) btwn the phenotypes of the two homozygotes

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12
Q

define codominance

A

phenotype of the heterozygote includes the phenotypes of both homozygotes

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13
Q

define penetrance

A

percentage of individuals having a particular genotype that expresses the expected phenotype

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14
Q

expressivity

A

the degree to which a character is expressed

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15
Q

complete penetrance

A

everyone who inherits the disease causing alleles has symptoms ex DMD

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16
Q

incomplete penetrance

A

some indivs do not express the phenotype even though they inherit the alleles ex polydactlyly

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17
Q

variable expression

A

symptoms vary in intensity in diff ppl ex 2 extra digits vs 3 extra digits in polydactlyly

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18
Q

_ and the _ who contributed the mutation affect the risk (penetrance)

A

sex and the parent who contributed

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19
Q

lethal alleles cause what on mendelian genotypic and phenotypic ratios in progeny

A

cause progeny to die so some genotypes may not appear among the progeny producing skewed ratios

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20
Q

what is an example of multiple alleles

A

ABO blood group; for a given locus, more than 2 alleles are present w/in a group of indivs

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21
Q

which blood type is codominant?

A

AB

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22
Q

what is gene interaction

A

interaction btwn alleles; interaction btwn 2 loci determine a single characteristic

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23
Q

gene interaction can produce _ phenotypes

24
Q

define gene interaction and describe gene interaction with epistasis

A

gene interaction effects of genes at one locus depend on the presence of genes at other loci and w/ epistasis one gene masks the effect of another gene

25
epistasis
interaction of genes that are not alleles in particular, one gene masks or influences the effect of another gene
26
recessive epistasis
*a recessive mutation in one gene masks the phenotypic effects of another* when the recessive allele of one gene masks the effect of either allele of the second gene
27
dominant epistasis
when the dominant allele of one gene masks the expression of all alleles of another gene
28
pleiotropy
one gene is able to affect multiple phenotypic characteristics ex sickle-cell disease and capillaries in eye, liver, and heart
29
complementation
2 strains of an organism with diff homozygous recessive mutations that produce the same mutant phenotype and produce offspring with the WT phenotype when mated or crossed
30
crossing pure breeding strains result in the mutant phenotype if
the mutations occur at a single locus
31
crossing pure breeding strains results in a wild type phenotype if
the mutations occur at different loci; WT masks mutant
32
in cystic fibrosis, why is disease symptoms viewed as complete dominance
a heterozygous CF carrier don't usu exhibit symptoms of CF; the normal and disease alleles show complete dominance
33
in cystic fibrosis, why is channel localizations viewed as codominant
at the cellular level, there will be normal channels at the membrane (from the normal allele) and trapped channels in the ER (from disease allele) ie both present
34
in cystic fibrosis, why is chloride transport viewed as incomplete dominance
the disease and normal alleles of CF may show chloride in sweat slightly above normal in heteros but not abnormal enough compared to homos
35
sex influenced traits
controlled by genes present on autosomes and expression responds differently to androgens or estrogens
36
sex-limited characteristics are inherited according to
mendel's principles; ex precocious puberty in humans. both male and female can transmit this sex limited trait, but it is expressed only in males
37
imprinted genes
are genes whose expression is determined by the parent that contributed them
38
genomic imprinting
certain genes are expressed in a parent-of-origin-specific manner; depending on if you are m/f, certain genes are modified based on your sex ex IGF2 locus paternal is active and maternal allele non-functional. SIGNIFICANT DEVIATION FROM MENDEL'S RULES
39
epigenetics
alterations to DNA that do not include changes in the base sequence; affect how DNA sequences are expressed
40
imprinting phenomenon increases with
organisms becoming more complex
41
epigentic trait
ex IGF2 gene; not a consequence of changes in DNA sequence. "stably heritable"
42
stably heritable mean
passed from one generation to the next and at the level of mitosis (mother to daughter cell)
43
genetic phenomenon: sex-linked characteristic
phenotype determined by: genes located on the sex chromosome
44
genetic phenomenon: sex-influenced characteristic
phenotype determined by: autosomal genes that are more readily expressed in one sex
45
genetic phenomenon: sex-limited characteristic
phenotype determined by: autosomal genes whose expression is limited to one sex
46
genetic phenomenon: genetic maternal effect
phenotype determined by: nuclear genotype of the maternal parent
47
genetic phenomenon: cytoplasmic inheritance
phenotype determined by: cytoplasmic genes, which are usually inherited from only one parent
48
genetic phenomenon: genomic imprinting
phenotype determined by: genes whose expression is affected by the sex of the transmitting parent
49
what is anticipation
COMMON PHENOTYPIC DISORDER AND DIFFERENT FROM MENDEL'S RULES genetic trait becomes more strongly expressed or expressed at an earlier stage as it is passed from generation to generation
50
how does anticipation occur
slippage in recombination, repetitive aas are incorporated in protein in blocks (3 nucleotides) causing duplications in regions (accumulation/expansion)
51
Fragile X mental retardation, why is it rare in females
FMR1 located on x chromosome thus more common in males bc an affected father and carrier mother which almost never happens bc of the impairment associated with it
52
discontinuous characteristics
relatively few phenotypes
53
continuous characteristics
continuous distribution of phenotypes; occurs when genes at many loci interact ex skin pigmentation
54
polygenic characteristics
result of many genes (genes at many loci) contributing to characteristics ex skin pigmentation
55
multifactorial traits/complex disorders
accumulation of variants of multiple genes and as they passed along in a family; influenced by a greater degree by environment
56
heterosis or hybrid vigor
importance in variation in a genome. Having 2 different alleles (hetero) is better for variation and in hybrids; hybrids are better than pure (homo) breeding ex mule

Genetics (37 decks)

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